Electrode foil for electrolytic capacitor and method for manufacturing the same

Abstract

A manufacturing method including: forming a boehmite film on a roughened surface of an aluminum foil; forming a particulate gel of a valve metal oxide on the surface of the aluminum foil on which the boehmite film is formed; then carrying out heat treatment for forming particulate valve metal oxide; and anodizing.

1 . A method of manufacturing an electrode foil for an electrolytic capacitor, the method comprising: 
 forming a boehmite film on a roughened surface of an aluminum foil;    forming a particulate gel of a valve metal on the surface of the aluminum foil on which the boehmite film is formed;    carrying out heat treatment for forming a particulate valve metal oxide from the particulate gel of a valve metal; and    anodizing the heat-treated aluminum foil.    
     
     
         2 . The method of manufacturing an electrode foil for an electrolytic capacitor according to  claim 1 , wherein the anodizing is carried out in such a manner in which the particulate valve metal oxide is covered with an amorphous dielectric oxide film layer.  
     
     
         3 . The method of manufacturing an electrode foil for an electrolytic capacitor according to  claim 1 , wherein the forming of the boehmite film comprises: 
 dipping the aluminum foil into a weak alkaline aqueous solution; and    carrying out heat treatment.    
     
     
         4 . The method of manufacturing an electrode foil for an electrolytic capacitor according to  claim 3 , wherein the weak alkaline aqueous solution is pH 8 to 10.  
     
     
         5 . The method of manufacturing an electrode foil for an electrolytic capacitor according to  claim 1 , wherein the forming of the particulate gel of valve metal is dipping the aluminum foil on which the boehmite film is formed into a sol solution containing the valve metal oxide particles having a particle size in a range of 1 to 200 μm.  
     
     
         6 . The method of manufacturing an electrode foil for an electrolytic capacitor according to  claim 5 , wherein the sol solution is containing metal oxide particles of at least one metal selected from Si, Ti, Zr, Nb, Al and Ta.  
     
     
         7 . An electrode foil for an electrolytic capacitor, comprising: 
 particulate valve metal oxide formed on a roughened surface of an aluminum foil; and    an amorphous dielectric oxide film layer covering the particulate valve metal oxide.    
     
     
         8 . The electrode foil for an electrolytic capacitor according to  claim 7 , wherein the valve metal is at least one metal selected from Si, Ti, Zr, Nb, Al and Ta.  
     
     
         9 . The electrode foil for an electrolytic capacitor according to  claim 7 , wherein the valve metal oxide is a particle having a particle size in a range of 1 to 200 μm.